Discussion The experiment we conducted at Pulpit Hill reserve near Monks Riseborough was to investigate if there was a significant difference between snail populations in different locations. Our raw results show that there was no difference in brown coloured shells between thin and thick populations, we found a larger difference in pink coloured shells between thin and thick locations we also found that the yellow snail shell colour was more abundant overall in both populations thick in comparison to pink and brown coloured shells. Some unusual results were found; the same numbers of brown snails were found in both thick and thin vegetation. This could be due to sampling error. We conducted a chi squared test with 2 degrees of freedom at a p value of 0.05 and found that our chi squared (4.877) was greater than the critical value (0.103) which suggest that our null hypothesis can be provisionally rejected at the 5% level. The observed significant difference of snail shell colour may be due to variables of genetic drift since there is a change in allele frequency within a population of C. Nemoralis. This could be due to selection since the alleles for yellow shell colour seem to be more advantageous in comparison to brown and pink shell snail colour as yellow shells highly populate the area we investigated. From this we can concluded that there is polymorphism in the population of C. Nemoralis at Pulpit Hill reserve which supports previous studies by Leith & Rawling (1977) and Cook (1998). On the other hand the significant difference could instead be due to sampling errors since we only conducted four repeats for each variable this may not be a significant amount to ensure our findings are accurate. Also important is the type of sampling carried out. Perhaps next time we could use a different sampling strategy e.g. quadrants or line transects. This could be more systematic, and would reduce the risk of collecting the same samples multiple times. Other limitations which may have influenced our findings could be due to the classification of the vegetations we decided to study. There was not a consistent definition of what thick and thin vegetation consisted of. When we gathered our data, it was fairly dry as it had only rained slightly. The optimum climate for snails is a wet environment. Therefore the sample we collected may not have been representative of the whole population. Overall we have found that there is polymorphism present in the in the population of C. Nemoralis, despite the potential limitations. However if this experiment was carried out again, we would take the factors discussed into consideration to reduce the sampling error.
The experiment we conducted at Pulpit Hill reserve near Monks Riseborough was to investigate if there was a significant difference between snail populations in different locations. Our raw results show that there was no difference in brown coloured shells between thin and thick populations, we found a larger difference in pink coloured shells between thin and thick locations we also found that the yellow snail shell colour was more abundant overall in both populations thick in comparison to pink and brown coloured shells. Some unusual results were found; the same numbers of brown snails were found in both thick and thin vegetation. This could be due to sampling error.
We conducted a chi squared test with 2 degrees of freedom at a p value of 0.05 and found that our chi squared (4.877) was greater than the critical value (0.103) which suggest that our null hypothesis can be provisionally rejected at the 5% level. The observed significant difference of snail shell colour may be due to variables of genetic drift since there is a change in allele frequency within a population of C. Nemoralis. This could be due to selection since the alleles for yellow shell colour seem to be more advantageous in comparison to brown and pink shell snail colour as yellow shells highly populate the area we investigated. From this we can concluded that there is polymorphism in the population of C. Nemoralis at Pulpit Hill reserve which supports previous studies by Leith & Rawling (1977) and Cook (1998).
On the other hand the significant difference could instead be due to sampling errors since we only conducted four repeats for each variable this may not be a significant amount to ensure our findings are accurate. Also important is the type of sampling carried out. Perhaps next time we could use a different sampling strategy e.g. quadrants or line transects. This could be more systematic, and would reduce the risk of collecting the same samples multiple times.
Other limitations which may have influenced our findings could be due to the classification of the vegetations we decided to study. There was not a consistent definition of what thick and thin vegetation consisted of. When we gathered our data, it was fairly dry as it had only rained slightly. The optimum climate for snails is a wet environment. Therefore the sample we collected may not have been representative of the whole population.
Overall we have found that there is polymorphism present in the in the population of C. Nemoralis, despite the potential limitations. However if this experiment was carried out again, we would take the factors discussed into consideration to reduce the sampling error.
Aleena Viepadan, Kimberley Dubois, Fazeelah Raja, Gbemi Babalola